Laser scanning method and system

Abstract

A laser scanning method and system for determining an outline of an object. A laser beam is projected at the object and a surface underlying the object. The surface is configured to reflect the laser beam differently than the object. The laser beam is reflected off the object and the surface producing reflected beams. The reflected beams are received by a control which determines whether the beam was reflected from the object or the surface. By identifying this with the laser position the control can identify the part outline. As the laser beam is scanned over successive positions along the surface, the outline of the object is precisely determined. In a preferred embodiment, the laser scanning system further includes a transparent support for supporting the object a predetermined distance from the surface thereby increasing the scanning resolution and improving the accuracy of the system.

We claim: 
     
       1. A method for determining an outline of a two-dimensional object comprising the steps of: (1) providing a laser projector for projecting a laser beam;   (2) providing a surface underlying said object;   (3) scanning said laser beam over said object and said surface;   (4) receiving a reflected beam;   (5) determining whether said reflected beam was reflected from said surface or said object; and   (6) determining said outline of said object based upon the determinations of step (5).   
     
     
       2. A method as recited in claim 1, wherein step (3) includes performing a coarse scan with said laser beam over said object and said surface to determine a starting position on said outline of said object. 
     
     
       3. A method as recited in claim 2, wherein step (3) includes performing a fine scan with said laser beam beginning at said staring position over successive positions along said outline of said object. 
     
     
       4. A method as recited in claim 1, wherein said surface is a retroreflective surface. 
     
     
       5. A method as recited in claim 1, wherein a control senses the qualities of the reflected beams from the object and the surface to determine whether a particular reflected beam is from the object or the surface, and said control associated said type of reflected beam with a particular location of the projected laser beam for identifying whether a particular location is object or surface. 
     
     
       6. A method as recited in claim 1, wherein a transparent support is provided for supporting said object a predetermined distance above said surface prior to step (3). 
     
     
       7. A method for determining an outline of a two-dimensional object comprising the steps of: (1) providing a laser projector for projecting a laser beam;   (2) providing a transparent support for supporting said object;   (3) providing a surface beneath said transparent support and said object;   (4) scanning said laser beam over said object and said surface;   (5) receiving a reflected beam;   (6) determining whether said reflected beam was reflected from said surface or said object; and   (7) determining said outline of said object based upon the determinations of step (6).   
     
     
       8. A method as recited in claim 7, wherein step (4) includes performing a coarse scan with said laser beam over said object and said surface to determine a starting position on said outline of said object. 
     
     
       9. A method as recited in claim 8, wherein step (4) includes performing a fine scan with said laser beam beginning at said starting position over successive positions along said outline of said object. 
     
     
       10. A method as recited in claim 7, wherein said surface is a retroreflective surface. 
     
     
       11. A method as recited in claim 7, wherein a control senses the qualities of the reflected beams from the object and the surface to determine whether a particular reflected beam is from the object or the surface, and said control associated said type of reflected beam with a particular location of the projected laser beam for identifying whether a particular location is object or surface. 
     
     
       12. A laser scanning system comprising: a laser projector for projecting a laser beam;   a transparent support for supporting an object;   a surface underlying said support for reflecting said laser beam, said surface configured to reflect said laser beam differently than the object; and   a control means for scanning said laser beam over the object and said surface and determining an outline of the object based upon whether said laser beam was reflected from one of the object and said surface.   
     
     
       13. A laser scanning system as recited in claim 12, wherein said control means includes a reflection sensor to receive a reflected laser beam. 
     
     
       14. A laser scanning system as recited in claim 12, further including a plurality of calibration targets to calibrate said laser scanning system. 
     
     
       15. The method of claim 1 wherein the surface and the object have distinguishable reflectivities.